The development of visual acuity is being studied in detail, by means of a behavioral technique, forced-choice preferential looking. The development of acuity is being followed longitudinally in individual infants, and additional infants are being studied cross-sectionally at the same ages used for testing the longitudinal sample. Preliminary age norms will be generated from this project. A quick, efficient version of the technique is also being developed for possible clinical screening of infant vision.